Sulfonated poly(arylene ether) copolymers and related polymer electrolyte membranes and fuel cells

ABSTRACT

The present invention relates to a sulfonated poly(arylene ether) copolymer, a manufacturing method thereof and a polymer electrolyte membrane for fuel cell using the same.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2009-0120130 filed in the Korean IntellectualProperty Office on Dec. 4, 2009, the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a sulfonated poly(arylene ether)copolymer, a manufacturing method thereof and a polymer electrolytemembrane for fuel cell using the same.

(b) Description of the Related Art

A fuel cell is an energy converting device that can convert chemicalenergy into electrical energy by an electrochemical reaction betweenhydrogen or methanol, which is a fuel, and oxygen or air, which is anoxidizing agent. A fuel cell may include a fuel electrode (anode), anoxygen electrode (cathode) and an electrolyte membrane that is disposedbetween the two electrodes. Such a configuration is called amembrane-electrode assembly. In such an assembly, the electrolytemembrane can facilitate transport of a hydrogen ion that is generated atthe fuel electrode to the oxygen electrode (the conductivity of thehydrogen ion is high) and a role as a partition for preventing fuel frombeing mixed with oxygen (dimensional stability to hydration is high andthe methanol transmissivity is low).

Such polymer electrolyte membranes (PEMs) can be classified asfluorinated PEMs and hydrocarbon-based PEMs. Hydrocarbon-basedelectrolyte membrane can be produced with polymers such as polyimide(PI), polysulfone (PSU), polyetherketone (PEK), polyarylene ethersulfone(PAES) and the like. Hydrocarbon-based electrolyte membranes can provideadvantages of low manufacturing costs and good thermal stabilityrelative to is excellent as compared to the fluorinated electrolytemembranes.

However, to provide the hydrogen ion conductivity in a hydrocarbon-basedelectrolyte membrane comparable to that of a fluorinated membrane, ahydrophilic ion group such as a sulfonic acid group and the like can beintroduced into a hydrocarbon-based electrolyte membrane. however,introducing such hydrophilic ion groups can deteriorate mechanicalproperties because of excessive swelling due to moisture and, which canlower the membrane stability and result in the problem of elution of aportion of sulfonated resin.

To address this problem, water solubility of the electrolyte membranecan be lowered by introducing a crosslinking structure to a raw materialresin by covalent bonding to suppress elution of the resin, or fluidityof the polymer chain can be increased by introducing the sulfonic acidgroup into the side chain of the polymer rather than the main chain ofthe polymer to improve the conductivity of the hydrogen ion. However,these approaches also present drawbacks including that the conductivityof the hydrogen ion can be undesirably low, in the case of thecrosslinking approach, the crosslinking of a large polymer can besynthetically difficult, a membrane manufacturing process using thecrosslinked polymer also can be difficult, and mechanical properties ofthe membrane may not be sufficient because the fluidity of the polymercan be lowered due to an increase in the polymer glass transitiontemperature (Tg).

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention andtherefore it may contain information that does not form the prior artthat is already known in this country to a person of ordinary skill inthe art.

SUMMARY OF THE INVENTION

One aspect of the invention provides new poly(arylene ether) copolymers.Preferred polymers of the invention can provide desirable mechanicalproperties as well as high hydrogen ion conductivity.

An embodiment of the present invention provides a method formanufacturing the copolymer.

Another embodiment of the present invention provides a polymerelectrolyte membrane using the copolymer.

Another embodiment of the present invention provides a poly(aryleneether) copolymer that is represented by Formula 1:

wherein

R is a hydrogen atom or a sulfonic acid group (—SO₃ ⁻M⁺), M+ is apositive ion such as lithium, sodium or potassium,

each Ar₁ is each independently one or more substituent groups that areselected from the group consisting of the following Formula 4a,

Ar₂ is each independently one or more substituent groups that areselected from the group consisting of the following Formula 5a,

X is in the range of 0.01 to 1.0,

n is an integer in the range of 10 to 800,

In addition, the present invention provides a method for manufacturingthe sulfonated poly(arylene ether) copolymer, which comprises the stepsof a) copolymerizing (i) 2,2′-bis(2-hydroxy-5-biphenylyl)propane, (ii)one or more monomers that are selected from the group consisting of thefollowing Formula 4b, and (iii) one or more monomers that are selectedfrom the group consisting of the following Formula 5b to thereby form aresin, and b) introducing a sulfonic acid group to the resin:

In the Formula 4b, each X is the same or different halogen group such asF, Cl, Br or I.

Yet another embodiment of the present invention provides a polymerelectrolyte membrane using the copolymer.

We have found, among other things, that through a method ofcopolymerizing a dihydroxy monomer and dihalide monomer and sulfonatingthem, it is possible to manufacture a polymer that is designed so thatthe side chain length of the hydrophilic portion of the copolymer isrelatively long and the sulfonic acid group is dense, the introductionamount of the sulfonic acid group can be easily controlled through achange in equivalent of the sulfonating agent, the polymer can bemanufactured by a simplified method, and the polymer electrolytemembrane that is manufactured by using the polymer has high hydrogen ionconductivity in an environment having of low moisture content, and showshigh dimensional stability even if it is exposed to moisture for a longtime.

The poly(arylene ether) copolymer according to an embodiment of thepresent invention is represented by the following Formula 1:

wherein

R is a hydrogen atom or a sulfonic acid group (—SO₃ ⁻M⁺), M+ is apositive ion,

Ar₁ is each independently one or more substituent groups that areselected from the group consisting of the following Formula 4a,

Ar₂ is each independently one or more substituent groups that areselected from the group consisting of the following Formula 5a,

X is in the range of 0.01 to 1.0,

n is an integer in the range of 10 to 800,

In certain preferred aspects, in Formula 1, n is 20 to 800. In addition,X is preferably 0.1 to 0.9, and more preferably 0.2 to 0.8.

Particularly, the sulfonated poly(arylene ether) copolymer according toa preferred embodiment of the present invention is represented by thefollowing Formula 3:

In the Formula 3, Ar₁, Ar₂, X and n are the same as those of Formula 1.

In certain preferred aspects, and without being bound by theory, in themain chain of the polymer, the hydrophilic portion can facilitatetransporting a hydrogen ion, and the hydrophobic portion can facilitatesupporting physical properties of a membrane, and the performance of thepolymer membrane can depend at least in part on the structure of thehydrophilic portion and hydrophobic portion.

Thus, in the case of a preferred polymer of Formula 3, the sulfonatedpoly(arylene ether) copolymer can be designed so that the side chainlength of the hydrophilic portion is relatively long and the sulfonicacid group is dense. Again without being bound by theory, such a polymerstructure configuration can provide dimensional stability to moisturethrough formation of effective ion channels and high hydrogen ionconductivity, and relatively widening the hydrophobic portion.

The sulfonated poly(arylene ether) copolymer may be manufactured bysulfonating the poly(arylene ether) copolymer that is represented by thefollowing Formula 2, and the manufacturing method thereof is furtherdisclosed herein.

In the Formula 2, Ar₁, Ar₂, X and n are the same as those of Formula 1.

The poly(arylene ether) copolymer of Formulas 1 to 3 according to thepresent invention suitably may be e.g. a random copolymer or blockcopolymer.

The molecular weight of the poly(arylene ether) copolymer of Formulas 1to 3 may suitably vary widely and preferably, the weight averagemolecular weight may be 10,000 to 1,000,000, and more preferably 30,000to 800,000. Optimal polymer weights for any particular system maysuitably be assessed by simple testing e.g. by analysis of mechanicalproperties and hydrogen ion conductivity of a polymer.

According to another embodiment, the present invention provides amanufacturing method of the sulfonated poly(arylene ether) copolymer,the method suitably comprising the steps of:

a) copolymerizing 2,2′-bis(2-hydroxy-5-biphenylyl)propane, one or moremonomers that are selected from the group consisting of the followingFormula 4b, and

one or more monomers that are selected from the group consisting of thefollowing Formula 5b, and

b) introducing a sulfonic acid group to the copolymerized polymer

In the Formula 5b, X is an atom that is each independently selected froma halogen group.

Various steps of manufacturing methods of the present invention aredescribed as follows. However, it will be understood that thesedescriptions are exemplary only, and that additional steps may beincluded in a method of the invention and/or one or more the describedsteps may be omitted or modified.

a) The Step for Copolymerizing the Monomer

Step a) includes polycondensation of the monomers to synthesize thepoly(arylene ether) copolymer according to Formula 2, and is suitablyperformed for example through reaction(s) that may comprise anucleophilic substitution reaction via an activation step and apolymerization step. The nucleophilic substitution reaction can beperformed under generally known conditions which are not particularlylimited.

In the step a) step, the X value of Formula 3 may be determinedaccording to the content ratio of each monomer, and preferably theequivalent ratio of one or more monomers that are selected from thegroup consisting of Formula 4b: 2,2′-bis(2-hydroxy-5-biphenylyl)propane:one or more monomers that are selected from the group consisting ofFormula 5b may be 1:0.05 to 0.95:0.05 to 0.95, and more preferably 1:0.2to 0.8:0.2 to 0.8.

According to an embodiment of the present invention, the contents oramounts of the monomers may be controlled and added in the range wherethe sum total of the mole number of[2,2′-bis(2-hydroxy-5-biphenylyl)propane] and the mole number of one ormore monomers that are selected from the group consisting of Formula 5bis the same as the mole number of one or more monomers that are selectedfrom the group consisting of Formula 4b. In more detail, for example,the equivalent ratio of one or more monomers that are selected from thegroup consisting of Formula 4b: [2,2′-bis(2-hydroxy-5-biphenylyl)propane]: one or more monomers that are selectedfrom the group consisting of Formula 5b may be (1:0.95:0.05),(1:0.9:0.1), (1:0.85:0.15), (1:0.8:0.2), (1:0.75:0.25), (1:0.7:0.3),(1:0.65:0.35), (1:0.6:0.4), (1:0.55:0.45), (1:0.5:0.5), (1:0.45:0.55),(1:0.4:0.6), (1:0.35:0.65), (1:0.3:0.7), (1:0.25:0.75), (1:0.2:0.8),(1:0.15:0.85), (1:0.1:0.9), or (1:0.05:0.95). It will be understoodhowever that these equivalent ratios are exemplary only and arenon-limiting.

In addition, the step a) may be performed in the presence of one or moresolvents that for example are suitably selected from the groupconsisting of dimethylacetamide, N-methylpyrrolidone, dimethylformamide,dimethyl sulfoxide, methylene chloride, chloroform, tetrahydrofuran,benzene, toluene and xylene.

According to a preferred embodiment of the present invention, the stepa) may be performed by mixing the monomers in one or more solvents suchas those disclosed above, performing the activation step at 100 to 180°C. for 2 to 4 hours, gradually increasing the temperature to 120 to 200°C., performing the polymerization reaction for 12 to 48 hours, thenwashing the resultant polymer with one or more solvents, and drying thewashed polymer.

In addition, if necessary or desired, a step for oxidizing themanufactured copolymer may be further performed. That is, in thesulfonating step described below, in the case of when the sulfonic acidgroup is introduced to an undesirable site of the main chain of thecopolymer, the polymer electrolyte membrane comprising such a polymermay exhibit lower dimensional stability and the uniformity of themembrane can be reduced because of a difference in partial ionconductivity between the membranes. Accordingly, in such instances wherethere is a site to which the sulfonic acid group is easily introduced inaddition to the R site of Formula 1, it can be preferred to perform afurther and subsequent oxidizing step to incorporate a sulfonic acidgroup on the polymer.

According to one embodiment of the present invention, in the case ofwhen the copolymer is manufactured by using 4,4′-thiodiphenol as one ormore monomers that are selected from the group consisting of Formula 5band the copolymer is directly sulfonated, the sulfonation may occur atan undesired site (specifically, 4,4′-thiodiphenol site) other than R ofFormula 1. To promote the desired sulfonation, it can be preferable tooxidize the 4,4′-thiodiphenol site before the sulfonation reaction.

Oxidation of the copolymer can be [performed by a wide variety ofmethods. In one preferred oxidation protocol, the copolymer can bedissolved in one or more organic solvents with the addition of asuitable oxidizing agent such as methachloroperoxybenzoic acid tothereby perform the oxidation reaction.

b) The Step for Introducing a Sulfonic Acid Group to the CopolymerizedPolymer

Step b) includes performing the sulfonation reaction of the poly(aryleneether) copolymer according to Formula 2 to manufacture the sulfonatedpoly(arylene ether) copolymer according to Formula 3.

The sulfonating reaction may be performed for example by reacting thecopolymer with a sulfonic acid compound. A variety of sulfonic acidcompounds may be employed in the sulfonating reaction including forexample one or more selected from the group consisting of concentratedsulphuric acid (H₂SO₄), chlorosulfonic acid (ClSO₃H), fuming sulfuricacid (fuming SO₃) and fuming sulfuric acid triethylphosphate salt(SO₃-TEP).

This step b) may be conducted within a wide range of reactiontemperatures for example at 0 to 100° C., and preferably 25 to 50° C.

According to an embodiment of the present invention, the step b) may beperformed by dissolving the copolymer that is synthesized in step a) inone or more solvents, adding the sulfonic acid compound thereto to andcontinuing the reaction for a suitable reaction time such as for 1 to 5hours, and filtering and drying the product.

According to another embodiment, the present invention provides apolymer electrolyte membrane that includes the sulfonated poly(aryleneether) copolymer.

The polymer electrolyte membrane may be suitably manufactured throughknown methods, except that the sulfonated poly(arylene ether) copolymeraccording to the present invention is used.

For example, in a preferred method, a polymer electrolyte membrane maybe manufactured by dissolving the sulfonated poly(arylene ether)copolymer in one or more organic solvents such as dimethylacetamide,dimethylacrylic acid (DMAc), N-methyl-2-pyrrolidone (NMP), anddimethylformamide (DMF), casting it on the glass plate and drying it atfor example 80 to 160° C.

A polymer electrolyte membrane of the invention also may comprisefurther components in addition to a sulfonated poly(arylene ether)copolymer according to the present invention according to the presentinvention. Such additional components may be suitably added with asulfonated poly(arylene ether) polymer in the manufacturing process of apolymer electrolyte membrane.

According to an embodiment of the present invention, in addition to thepoly(arylene ether) copolymer, as the proton conductive polymer, one ormore polymers selected from the group consisting of polyimide,polyetherketone, polysulfone, polyethersulfone, polyetherethersulfone,polybenzimidazole, polyphenyl oxide, polyphenylene sulfide, polystyrene,polytrifluorostyrene sulfonic acid, polystyrene sulfonic acid,polyurethane and branched sulfonated polysulfoneketone copolymer may befurther included in a polymer electrolyte membrane together with one ormore poly(arylene ether) copolymers.

One or more inorganic materials that are selected from the groupconsisting of silicon oxide SiO₂, titanium oxide TiO₂, inorganicphosphoric acid, sulfonated silicon oxide (Sulfonated SiO₂), sulfonatedzirconium oxide (sulfonated ZrO) and sulfonated zirconium phosphate(sulfonated ZrP) may be further included in a polymer electrolytemembrane together with one or more poly(arylene ether) copolymers.

The polymer electrolyte membrane of the present invention may besuitably used in a Membrane-Electrode Assembly that includes a fuelelectrode (anode), an oxygen electrode (cathode) and an electrolytemembrane that is disposed between the two electrodes. Such components ofa Membrane-electrode Assembly are not in general particularly limited.

Since the polymer electrolyte membrane is manufactured by using thesulfonated poly(arylene ether) copolymer according to the presentinvention, thermal and chemical stability, and processability can beexcellent, high hydrogen ion conductivity can be provided due to thesubstituted sulfonic acid group, and even if the system is exposed tomoisture for extended time periods, there can be little change inelectrolyte membrane characteristics, such that high dimensionalstability can be exhibited. Thus, polymer electrolyte membranes of heinvention can provide excellent performance properties and can be highlyuseful in battery fields such as for use as a fuel battery orrechargeable battery.

In certain preferred aspects, a sulfonated poly(arylene ether) copolymeraccording to the present invention can be provided with an extended(long) side chain length of the hydrophilic portion and relatively highdensity of sulfonic acid groups. Additionally, polymer membranes of theinvention can provide dimensional stability to moisture through formingeffective ion channels and relatively widening the hydrophobic portion.

In addition, through preferred manufacturing methods of the presentinvention, the introduction amount of the sulfonic acid group can beeasily controlled through a change in equivalent of the sulfonatingagent, the polymer can be manufactured by a simplified method, and thepolymer electrolyte membrane that is manufactured by using the polymercan have a relatively high hydrogen ion conductivity in an environmenthaving low moisture content, and can exhibit high dimensional stabilityeven if it is exposed to moisture for extended time periods such as theproduced polymer electrolyte membranes can be highly useful including asfuel cells.

Additionally, systems of the invention are highly useful in vehiclesincluding motor vehicles such as automobiles (which includes passengervehicles, buses, commercial vehicles, etc.), particularly vehicles thatutilize a fuel cell.

Other aspects of the invention are disclosed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph that illustrates a nuclear magnetic resonance (NMR)spectrum in respects to the polyarylene ether copolymer [step (a) of themanufacturing method] according to Examples 1 to 3 of the presentinvention; and

FIG. 2 is a graph that illustrates a nuclear magnetic resonance (NMR)spectrum in respects to the sulfonated polyarylene ether copolymer [step(b) of the manufacturing method] according to Examples 1 to 3 of thepresent invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Preferred examples are herein described. However, the following Examplesare set forth to illustrate and should not to be construed to limit thepresent invention.

Example 1 a) Manufacturing of Poly(Arylene Ether) Copolymer (X=0.4)

As shown in Reaction Equation (1-a), under a nitrogen atmosphere, inequipment that included a condenser Dean-Stark trap and a magneticstirrer bar, to a two-neck round bottom flask, as the monomer,4,4′-difluorodiphenylsulfone [20 mmol],2,2′-bis(2-hydroxy-5-biphenylyl)propane [8 mmol] and4,4′-(hexafluoroisopropylidene)diphenol [12 mmol] were put as themonomer, and potassium carbonate (24 mmol) was added thereto. At thistime, dimethylacetamide (70 mL) and toluene (50 mL) were added theretoas the reaction solvent.

The activation step was performed at the reaction temperature of 140° C.for 4 hours, and in the reaction, water that was manufactured as thebyproduct was removed by toluene which was the reaction solvent. Thepolymerization reaction was performed for 24 hours by graduallyincreasing the temperature to 165° C. After the reaction was finished,it was washed several times with methanol/water (volume ratio=1:1), andvacuum dried at 60° C. for 24 hours.

The final product was obtained in a white solid form (yield: 95%), and¹H-NMR was performed to analyze the structure, and the results thereofare shown in FIG. 1.

b) Manufacturing of the Sulfonated Poly(Arylene Ether) Copolymer

Under a nitrogen atmosphere, in equipment that was provided with thecondenser, the dropping funnel and the magnetic stirrer bar, in thetwo-neck round bottom flask, 2.0 mmol of the copolymer that wassynthesized in step (a) was dissolved in 20 mL of dichloromethane, andthe mixture solution of 4.8 mmol of chlorosulfonic acid and 20 mL ofdichloromethane was slowly dropped thereon for 1 hour. At this time, thereaction temperature was room temperature, and the reaction time was 3hours.

When sulfonation was performed, the solubility in dichloromethane wasreduced to form the sulfonated polymer precipitate. After the reactionwas finished, it was washed several times by using hexane and distilledwater to remove the remaining chlorosulfonic acid. After the reactionwas finished, it was filtered and vacuum dried.

After the dried copolymer was dissolved in dimethylacetamide solution,the potassium hydroxide aqueous solution having the concentration of 3wt % was dropped thereon, and the pH was controlled to be neutral byusing the chloric acid solution. Thereafter, the target sulfonatedpolyarylene ether copolymer was synthesized by filtering the copolymerand vacuum-drying it.

The final product was subjected to ¹H-NMR to analyze the structure, andthe results thereof are shown in FIG. 2. As shown in FIG. 2, the peakwas generated at around 7.50 ppm while the sulfonic acid group wasintroduced to the copolymer, which meant that hydrogen at the alphaposition of the sulfonic acid group became the down field, and throughthe area ratio, it was confirmed that the synthesis was accomplished.

Example 2 a) Manufacturing of Poly(Arylene Ether) Copolymer (X=0.6)

The copolymer was manufactured by using the same condition and method asstep (a) of Example 1, except that the molar ratio of the monomers wasset so that 4,4′-difluorodiphenylsulfone [20 mmol], 2,2′-bis(2-hydroxy-5-biphenylyl)propane [12 mmol] and4,4′-(hexafluoroisopropylidine)diphenol [8 mmol] were added. The finalproduct was obtained in a white solid form, and ¹H-NMR was performed toanalyze the structure, and the results thereof are shown in FIG. 1.

b) Manufacturing of the Sulfonated Poly(Arylene Ether) Copolymer

The sulfonated copolymer was performed by using the same condition andmethod as step (b) of Example 1, except that the copolymer that wassynthesized in step (a) was used.

The final product was subjected to ¹H-NMR to analyze the structure, andthe results thereof are shown in FIG. 2. As shown in FIG. 2, the peakwas generated at around 7.50 ppm while the sulfonic acid group wasintroduced to the copolymer, which meant that hydrogen at the alphaposition of the sulfonic acid group became the down field, and throughthe area ratio, it was confirmed that the synthesis was accomplished.

Example 3 a) Manufacturing of Poly(Arylene Ether) Copolymer (X=0.8)

The copolymer was manufactured by using the same condition and method asstep (a) of Example 1, except that the molar ratio of the monomers wasset so that 4,4′-difluorodiphenylsulfone [20 mmol], 2,2′-bis(2-hydroxy-5-biphenylyl)propane [16 mmol] and4,4′-(hexafluoroisopropylidine)diphenol [4 mmol] were added. The finalproduct was obtained in a white solid form, and ¹H-NMR was performed toanalyze the structure, and the results thereof are shown in FIG. 1.

b) Manufacturing of the Sulfonated Poly(Arylene Ether) Copolymer

The sulfonated copolymer was performed by using the same condition andmethod as step (b) of Example 1, except that the copolymer that wassynthesized in step (a) was used.

The final product was subjected to ¹H-NMR to analyze the structure, andthe results thereof are shown in FIG. 2. As shown in FIG. 2, the peakwas generated at around 7.50 ppm while the sulfonic acid group wasintroduced to the copolymer, which meant that hydrogen at the alphaposition of the sulfonic acid group became the down field, and throughthe area ratio, it was confirmed that the synthesis was accomplished.

Preparation Example 1 Manufacturing of the Positive Ion Exchange PolymerElectrolyte Membrane

The sulfonated poly(arylene ether) copolymer that was manufactured instep (b) of Example 1 was dissolved in dimethylacetamide, cast on theglass plate, and dried at 120° C. to manufacture the polymer electrolytemembrane.

Preparation Example 2

Manufacturing of the Positive Ion Exchange Polymer Electrolyte Membrane

The polymer electrolyte membrane was manufactured by using the samemethod as Preparation Example 1, except that the sulfonated poly(aryleneether) copolymer that was manufactured in step (b) of Example 2 wasused.

Preparation Example 3 Manufacturing of the Positive Ion Exchange PolymerElectrolyte Membrane

The polymer electrolyte membrane was manufactured by using the samemethod as Preparation Example 1, except that the sulfonated poly(aryleneether) copolymer that was manufactured in step (b) of Example 3 wasused.

Comparative Example

The positive ion exchange polymer electrolyte membrane (Manufacturingcompany: DuPont, trademark: Nat ion-211) that was commercially sold wasprepared.

Experimental Example Measurement of the Molecular Weight andDispersibility of the Copolymer

The weight average molecular weight (Mw) and dispersibility (PDI=Mw/Mn)of the sulfonated poly(arylene ether) copolymer manufactured in Examples1 to 3 were measured by using chromatography, and the results thereofare described in the following Table 1. The equipment and condition usedin the measurement are described below.

-   -   GPC: Waters, Co., Ltd., model name 2414    -   Column: Waters, Co., Ltd., model name HR 3,4,5 column    -   temperature: 80° C./elution solvent: dimethylformamide/elution        speed: 1 ml/min    -   standard material: polymethylmethacrylate (PMMA)

The Degree of Sulfonation of the Copolymer

The degree of sulfonation (%) of the sulfonated poly(arylene ether)copolymer manufactured in Examples 1 to 3 were measured by using theNMR, and the results thereof are described in the following Table 1.

Measurement of the Hydrogen Ion Conductivity

The hydrogen ion conductivity of the polymer electrolyte membranemanufactured in Preparation Examples 1 to 3 and the Comparative Examplewere measured by using the impedance spectroscopy (manufactured bySolartron, Co., Ltd.), and the results thereof are described in thefollowing Table 1.

At this time, the impedance measurement condition was measured at thefrequency in the range of 1 Hz to 1 MHz, and the measurement wasperformed in an in-plane manner, and all tests were performed while thesamples were completely wet.

Measurement of the Methanol Transmissivity

After the polymer electrolyte membrane according to Preparation Examples1 to 3 and the Comparative Example was disposed between two cells, 15 mLof 1M methanol aqueous solution was injected into one cell, 15 mL ofdistilled water was injected into the other cell, 10 μl of samples werecollected every 10 min from the cell into which the distilled water wasinjected, and 10 μl of distilled water was provided again thereto. Themethanol concentration of the collected sample was measured by using thegas chromatography.

The change in methanol concentration according to time was recorded byusing the graph, methanol transmissivity was calculated from the slopethereof using the following Equation, and the results thereof aredescribed in the following Table 1.

$\begin{matrix}{{{Transmissivity}\;\lbrack {{cm}^{2}\text{/}\sec} \rbrack} = \frac{\begin{matrix}( {{{Slope}\lbrack {{ppm}\text{/}s} \rbrack} \times {SolutionVolume}\; \times}  \\ {ElectrolyteMembraneThickness}\; )\end{matrix}}{\begin{matrix}( {{ElectrolyteMembraneArea} \times}  \\ {MethanolConcentration}\mspace{11mu} )\end{matrix}}} & \lbrack{Equation}\rbrack\end{matrix}$

TABLE 1 The Weight degree of average Hydrogen ion Methanol sulfonationmolecular conductivity transmissivity Classification (%) weight × 10³Dispersibility (×10⁻³ S/cm) (×10⁻⁶ cm²/sec) Preparation 40 123 2.87 0.60.11 example 1 Preparation 60 115 2.46 3.0 0.56 example 2 Preparation 80183 2.97 5.8 0.94 example 3 Comparative — — — 3.5 2.10 Example

As shown in Table 1, since the electrolyte membrane according toPreparation Examples 1 to 3 of the present invention is manufactured byusing the sulfonated poly (arylene ether) copolymer of Examples 1 to 3,the degree of sulfonation is high and the weight average molecularweight is high. Thus, as compared to the known polymer electrolytemembrane (Comparative Example), the same or higher hydrogen ionconductivity and low methanol transmissivity are shown, such thatperformance as the polymer electrolyte membrane for fuel cell isexcellent.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

1. A poly(arylene ether) copolymer that is represented by Formula 1:

wherein, R is a sulfonic acid group (—SO₃ ⁻M⁺), M+ is a positive ion,Ar₁ is each independently one or more substituent groups that areselected from the group consisting of the following Formula 4a,

Ar₂ is each independently one or more substituent groups that areselected from the group consisting of the following Formula 5a,

X is in the range of 0.01 to 1.0, n is an integer in the range of 10 to800.
 2. A sulfonated poly(arylene ether) copolymer that is representedby Formula 3:

wherein, Ar₁, Ar₂, X and n are the same as those of Formula 1 ofclaim
 1. 3. The poly(arylene ether) copolymer of claim 1, wherein: thecopolymer is a random copolymer or block copolymer.
 4. The poly(aryleneether) copolymer of claim 1, wherein: X is in the range of 0.1 to 0.9.5. The poly(arylene ether) copolymer of claim 1, wherein: X is in therange of 0.2 to 0.8.
 6. The poly(arylene ether) copolymer of claim 1,wherein: a weight average molecular weight is in the range of 10,000 to1,000,000.
 7. The poly(arylene ether) copolymer of claim 1, wherein: theweight average molecular weight is in the range of 30,000 to 800,000. 8.A method for manufacturing the sulfonated poly(arylene ether) copolymeraccording to claim 2, the method comprising the steps of: a)copolymerizing 2,2′-bis(2-hydroxy-5-biphenylyl)propane, one or moremonomers that are selected from the group consisting of the followingFormula 4b, and one or more monomers that are selected from the groupconsisting of the following Formula 5b, and b) introducing a sulfonicacid group to the copolymerized polymer:

wherein, X is an atom that is each independently selected from a halogengroup.
 9. The method for manufacturing the poly(arylene ether) copolymerof claim 8, wherein: the step a) of copolymerizing the monomer iscarried out so that an equivalent ratio of one or more monomers that areselected from the group consisting of Formula 4b:2,2′-bis(2-hydroxy-5-biphenylyl)propane: one or more monomers that areselected from the group consisting of Formula 5b is 1:0.05 to 0.95:0.05to 0.95.
 10. The method for manufacturing the poly(arylene ether)copolymer of claim 8, wherein: the step a) of copolymerizing the monomeris carried out so that an equivalent ratio of one or more monomers thatare selected from the group consisting of Formula 4b:2,2′-bis(2-hydroxy-5-biphenylyl)propane: one or more monomers that areselected from the group consisting of Formula 5b is 1:0.2 to 0.8:0.2 to0.8.
 11. The method for manufacturing the poly(arylene ether) copolymerof claim 9, wherein: step a) of copolymerizing the monomer is carriedout under the presence of one or more solvents that are selected fromthe group consisting of dimethylacetamide, N-methylpyrrolidone,dimethylformamide, dimethyl sulfoxide, methylene chloride, chloroform,tetrahydrofuran, benzene, toluene and xylene.
 12. The method formanufacturing the poly(arylene ether) copolymer of claim 8, comprisingthe steps of: a) copolymerizing the monomer; a-1) oxidizing thecopolymer; and b) introducing the sulfonic acid group to the oxidizedcopolymer.
 13. The method for manufacturing the poly(arylene ether)copolymer of claim 8, wherein: the step b) of introducing the sulfonicacid group to the copolymerized polymer is carried out by using one ormore sulfonic acid compounds that are selected from the group consistingof concentrated sulphuric acid (H₂SO₄), chlorosulfonic acid (ClSO₃H),fuming sulfuric acid (fuming SO₃) and fuming sulfuric triethylphosphatesalt (SO₃-TEP).
 14. The method for manufacturing the poly(arylene ether)copolymer of claim 8, wherein: the step b) of introducing the sulfonicacid group to the copolymerized polymer is carried out at a temperaturein the range of 0 to 100° C.
 15. A polymer electrolyte membranecomprising the sulfonated poly(arylene ether) copolymer that has thesulfonic acid group of claim
 2. 16. The polymer electrolyte membrane ofclaim 15, wherein: the polymer electrolyte membrane further includes atleast one of polymer that is selected from the group consisting ofpolyimide, polyetherketone, polysulfone, polyethersulfone,polyetherethersulfone, polybenzimidazole, polyphenylene oxide,polyphenylene sulphide, polystyrene, polytrifluorostyrene sulfonic acid,polystyrene sulfonic acid, polyurethane and branched-chained sulfonatedpolysulfoneketone copolymer.
 17. The polymer electrolyte membrane ofclaim 15, wherein: the polymer electrolyte membrane further includes oneor more inorganic materials that are selected from the group consistingof silicon oxide SiO₂, titanium oxide TiO₂, inorganic phosphoric acid,sulfonated silicon oxide (sulfonated SiO₂), sulfonated zirconium oxide(sulfonated ZrO) and sulfonated zirconium phosphate (sulfonated ZrP).18. The polymer electrolyte membrane of claim 15, wherein: theelectrolyte membrane is a polymer electrolyte membrane for fuel cell.19. A membrane-electrode assembly comprising the polymer electrolytemembrane of claim
 18. 20. The poly(arylene ether) copolymer of claim 2,wherein: the copolymer is a random copolymer or block copolymer.
 21. Thepoly(arylene ether) copolymer of claim 2, wherein: X is in the range of0.1 to 0.9.
 22. The poly(arylene ether) copolymer of claim 2, wherein: Xis in the range of 0.2 to 0.8.
 23. The poly(arylene ether) copolymer ofclaim 2, wherein: a weight average molecular weight is in the range of10,000 to 1,000,000.
 24. The poly(arylene ether) copolymer of claim 2,wherein: the weight average molecular weight is in the range of 30,000to 800,000.